NATO member Turkey does not view Finland and Sweden's bid to join the alliance positively, President Recep Tayyip Erdogan said on Friday, accusing both countries of aiding terrorism.
"We are monitoring the developments, but we do not have a positive view on this," Erdogan told reporters in Istanbul.
Scandinavian countries have become "like a guest house" for terrorist organizations, Erdogan argued, adding groups like the outlawed Kurdistan Workers' Party (PKK) and others are "even in parliaments" of Sweden and the Netherlands.
"It is not possible that we look at this positively," Erdogan added.
Turkey does not want to repeat the "mistake" it says it committed when Ankara approved Greece’s return to NATO’s integrated military structure in 1980, Erdogan separately argued.
He accused Athens of manipulating the NATO against Turkey.
Neighbouring Turkey and Greece are at odds regarding maritime rights in the Eastern Mediterranean, among other issues.
Finland and neighbouring Sweden are already close partners of NATO, yet have not become official members. Russia's invasion of Ukraine has sparked an intense debate to join NATO in both countries.
Sweden is likely to benefit from NATO membership, according to a defence analysis released by the Swedish government on Friday.
"Swedish NATO membership would raise the bar for military conflict and thus have a preventative effect on conflict in northern Europe," the analysis said, though it did not specifically recommend or advise against joining NATO.
However, as the report will be reviewed by lawmakers mulling the question, the document is likely to be influential.
"We can ascertain that the Russian crisis is structural, systematic and protracted," said Foreign Minister Ann Linde.
The report was drafted by members of the government, as well as members of various parliamentary parties. The country's Green and Left parties were the only ones to dispute the report's findings.
The biggest change envisaged by the report is that Sweden's defence would be protected by all NATO member states. The report noted that joining NATO would not only boost Swedish security, but also that of its neighbours.
Possible downsides to membership focused on Russia's likely reaction to the move, which it has publicly urged Sweden against. The report suggested cyberattacks could be used.
Sweden has traditionally been a neutral country, but Russia's recent invasion of Ukraine drastically swayed opinions, both among the Swedish public and in political circles. A similar shift is under way in Finland.
The government expects to draft an official opinion on its NATO stance on Sunday. If it decides in favour of NATO membership, the country could apply for membership as early as Monday.